Biomass Gasifier Definition

Agricultural waste is a common source of biomass for gasification plants like this one in rural Germany.

Biomass is plant material that can be converted into fuel -- when you burn wood to heat your home, you're heating with biomass. However, burning plant material does not make full use of its potential energy. The process of gasification efficiently converts the majority of plant material into fuel for applications such as heating homes and powering vehicles. The conversion of plant material into energy takes place inside a biomass gasifier.

Gasification

During gasification, plant material goes through two stages to efficiently extract its energy. In the first step, called pyrolysis, the material is burnt to produce volatile hydrocarbons and char. By treating the hydrocarbons and char with more heat, and the proper mix of oxygen, steam and air, the gasifier produces syngas. This gas can then be used for energy in much the same way as natural gas. The entire process occurs within a biomass gasifier. (See References 1, 2 and 3)

Types of Gasifiers

Biomass gasifiers provide a controlled and pressurized environment for gasification. Four types of biomass gasifiers are in use today: the counter-current fixed bed gasifier, the co-current fixed bed gasifier, the fluidized bed gasifier and the entrained flow gasifier. Because the counter-current and co-current types both operate at lower temperatures than the entrained flow types, the gas they produce contains tar that must be cleaned from the gas before it can be used. The entrained flow gasifier requires high temperatures to operate, but the gas produced does not need to be cleaned. Fluidized gasifiers work at lower temperatures, but produce a corrosive ash. (See References 1 and 3)

Benefits of Gasifiers

Instead of using finite fossil fuel resources, biomass gasifiers produce energy from renewable, domestically produced plant sources and plant waste to produce energy. Although gasifiers release carbon dioxide, when plants grow in nature they take up carbon dioxide, making gasification a carbon neutral energy source. (See References 1 and 2)

Current Uses

Biomass gasifiers produced 3 percent of the energy in the United States in 2006. The gas produced is used to heat homes, produce electricity and power vehicles. With a shifting focus on increasing the nation's energy independence, more biomass gasifiers will be used to produce clean energy from local sources. (See References 1 and 2)